Adhesive film for adhesive bandage and adhesive bandage using said adhesive film

ABSTRACT

[CONSTRUCTION] 
     An adhesive film for adhesive bandage formed by coating an adhesive to a nonwoven fabric comprising 50 to 80% by weight of a styrenic elastomer and 50 to 20% by weight of a polyolefine, and an adhesive bandage using said adhesive film.  
     [EFFECTS] 
     The adhesive bandage using the adhesive film for adhesive bandage of the present invention is rich in flexibility and excellent in fitness to a skin, and can prevent physical skin irritation. Because of high moisture permeability, skin respiration is not disturbed and skin irritation caused by being sticky with perspiration is also preventable. Blending of the polyolefine increases strength of the nonwoven fabric itself and imparts strength that does not give any trouble in practical use. Besides, in case of subjecting the surface to a water-repellent finish, it is possible to thoroughly prevent permeation of water into the nonwoven fabric and permeation of water into a pad portion.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0001] This invention relates to an adhesive film for adhesive bandageand an adhesive bandage using said adhesive film. More specifically,this invention relates to an adhesive film for adhesive bandage havingless skin irritation, said film using as a support a nonwoven fabriccomprising 50 to 80% by weight of a styrenic elastomer and 50 to 20% byweight of a polyolefine, and to an adhesive bandage using said adhesivefilm.

PRIOR ART AND PROBLEMS THE INVENTION SEEKS TO SOLVE

[0002] As an adhesive to a film for adhesive bandage, a product formedby coating an adhesive to a film of vinyl chloride, polyethylene,polypropylene or the like has been hitherto used in many cases. Amaterial such as vinyl chloride, polyethylene, polypropylene or the likeis, however, low in moisture permeability; when said material is used inan adhesive bandage and adhered to a skin, it tends to prevent skinrespiration and cause skin irritation too.

[0003] To prevent same, measure such as formation of air holes in afilm, etc. have been taken. However, skin respiration is locallyprevented and the air holes cause permeation of water into a pad portionand decrease in strength of a film. Moreover, as the film is lessflexible than the skin, it also allows physical irritation to a skin.

MEANS FOR SOLVING THE PROBLEMS

[0004] This invention aims to solve the aforesaid problems by importingsufficient moisture permeability and sufficient flexibility to a filmand an adhesive. That is, this invention aims to solve such problems byusing an adhesive film for adhesive bandage formed by wholly coating anadhesive, preferably a porous adhesive, to a nonwoven fabric comprising50 to 80% by weight of a styrenic elastomer and 50 to 20% by weight of apolyolefine.

[0005] The styrenic elastomer used in this invention widely includeselastomers formed by copolymerizing styrene as a comonomer with theother comonomer. Examples of the other comonomer can be monomerscopolymerizable with styrene, for example diene compounds such asbutadiene, isoprene and chloroprene, olefines such as ethylene,propylene, butene and hexene, (meth)acrylic acid, and esters of(meth)acrylic acid and alcohols such as methanol, ethanol, butanol andhexanol. A block copolymer composed of blocks of a hard portion and asoft portion is preferable. Especially preferable is a block copolymercomprising a hard portion of polystyrene and a soft portion ofpolyisoprene, especially hydrogenated polyisoprene. The hydrogenationreaction can be performed in a nonpolar solvent using a metalliccatalyst such as platinum, palladium, nickel, cobalt or the like.Percent hydrogenation is preferably 80% or more, more preferably 90% ormore based on the total amount of the double bond. With percenthydrogenation of less than 80%, a nonwoven fabric having sufficientweather resistance may not be obtained.

[0006] Such block copolymer is rich in flexibility with low modulus andexcellent in compression set, heat resistance, weather resistance andlow-temperature properties and the features above are owing to thestructural characteristics having the hard and soft portions. Itssynthesis method is described in, for example, Japanese Laid-open PatentAppln. (Kokai) Nos. 11059/92 and 136250/92. It is advisable that theamount of such polystyrene block is 10 to 50% by weight based on thetotal weight of the block copolymer. When it exceeds 50% by weight,stretchability becomes insufficient. When it is less than 10% by weight,tensile strength becomes insufficient.

[0007] Examples of the polyolefine of the present invention can be ahomopolymer of an olefine such as ethylene, propylene, butene orpentene, a copolymer of two or more of these olefines, etc. Of these,polypropylene is preferable.

[0008] The adhesive film for adhesive bandage of the present inventionuses a nonwoven fabric comprising a styrenic elastomer and apolyolefine. Namely, a nonwoven fabric made only of the styrenicelastomer is rich in flexibility but poor in mechanical strength and lowin breaking strength. When it is, however, blended with a polyolefine,mechanical strength and break strength can greatly be improved. On thisoccasion, in general, the flexibility gradually decreases with increasein polyolefine content.

[0009] The polyolefine content of the adhesive film for adhesive bandageof the present invention is 20 to 50% by weight. When the polyolefinecontent is less than 20% by weight, sufficient strength may not beobtained. When the polyolefine content exceeds 50% by weight,flexibility becomes insufficient.

[0010] The adhesive film for adhesive bandage of the present inventioncan be improved in moldability, if required, by adding a paraffin oiland so forth. A variety of known additives can be used to improveweather resistance, heat resistance, and so forth, of the material.

[0011] The adhesive used in the adhesive film for adhesive bandage ofthe present invention is not particularly limited if the skin is littleirritated and adhesion to the skin is provided; a rubbery adhesive, anacrylic adhesive, and an adhesive of an SIS block copolymer areavailable. Such adhesive can be coated on the whole adhesive surface ofthe nonwoven fabric. Preferably, in order to prevent decrease inmoisture permeability, a porous adhesive is coated or an adhesive is notwholly coated but pattern-coated.

[0012] As a method for making the adhesive porous, a method can be takenwhich comprises using a highly water-absorbable polymer as a blowingagent, conducting water absorption, then dispersing it in an adhesivesolution, coating the dispersion, and evaporating the moisture to makethe adhesive porous. However, said method is not critical.

[0013] Regarding the pattern coating, the adhesive can be coated on thesupport by, for example, screen coating method or gravure coatingmethod. However, these coatings are not critical.

[0014] As a method for coating an adhesive, there can be employed amethod in which the adhesive is directly coated on the nonwoven fabric,a method in which the adhesive is coated on a release paper and thentransferred onto the nonwoven fabric, and so forth.

[0015] The nonwoven fabric used as the support of the adhesive film foradhesive bandage of the present invention is easy to absorb water, whichat times gives rise to a problem that said fabric as such causes waterto permeate the inside of the film. Accordingly, it is advisable thatthe opposite surface to the adhesive coated surface is subjected to awater-repellent finish. This can almost completely prevent thepermeation of water into the nonwoven fabric. Examples of thewater-repellent are a silicon-type water-repellent, a fluorine-typewater-repellent and so forth. However, they are not critical.

[0016] The adhesive film for adhesive bandage of the present inventionmay be formed into the adhesive bandage by any method. Examples of themethod are a method in which when the adhesive is not stuck on theopposite surface to the adhesive coated surface, a long film having asuitable width is wound up to form an adhesive bandage, a method inwhich a sheet of a suitable size is provided, a pad is held on itscenter, and the adhering surface is covered with a release paper to forman individual pack of the adhesive bandage, and so forth.

[0017] This invention is illustrated by the following Examples morespecifically.

EXAMPLES

[0018] In Examples, properties were evaluated according to the followingmethods.

[0019] (1) Modulus:

[0020] A sample was cut to a width of 25.4 mm (1 inch), and the cutpiece was attached to a tensile testing machine at an interval of 50 mm.A load was measured when the test piece was stretched 5%, 10% and 100%at a drawing rate of 100 mm/min.

[0021] (2) Tensile Strength at Break and Tensile Elongation at Break:

[0022] A sample was cut to a width of 25.4 mm (1 inch), and cut piecewas attached to a tensile testing machine at an interval of 50 mm. Thetest piece was drawn at a drawing rate of 100 mm/min. A load andelongation were measured when the test piece was broken.

[0023] (3) Adhesion to glass:

[0024] A sample was cut to a width of 25.4 mm (1 inch), and adhered to aglass well washed with acetone. A load was applied thereto by onereciprocation with a roller in which a rubber was wound on an iron corehaving a weight of 4.5 kg. The glass with the test piece adhered theretowas attached to a tensile testing machine. A drawing rate was set at 300mm/min, and a load was measured when the test piece was peeled off fromthe glass surface.

[0025] (4) Moisture Permeability:

[0026] A sample was adhered to a ring of a moisture permeation cupaccording to JIS Z 0208, and surely mounted on a guide having alaboratory dish filled with water. Said sample mounted on the guide wasplaced in a constant-temperature (32° C.)/constant-humidity (30 RH %)device. A weight was measured hourly, which was repeated until a weightdifference per hour became stable. Moisture permeability was found froma value of decrease in weight per hour.

[0027] (5) Water-repellency:

[0028] 0.1 ml of water or a 0.75% detergent aqueous solution was droppedon a surface of a sample from a height of 2 cm. A time was measured thatlapsed from the time when the solution was dropped to the time when thesolution completely permeated the sample.

[0029] (6) Evaluation of Skin Irritation:

[0030] Skin irritation was evaluated by a patch test under the followingevaluation conditions.

[0031] a. Specimens

[0032] Adhesive bandage using the adhesive film for adhesive bandage inthis invention (Examples). Commercial adhesive bandage using a polyvinylchloride film (Comparative Example).

[0033] b. Subject

[0034] Grown-up men and women in good health, from 25 to 50 years old—44persons.

[0035] c. Test Method

[0036] Two types of specimens were adhered to an inside portion of anupper arm of each person. An adhesive expandable gauze bandage (tradename: Silky Pore) made by Tokyo Eizai Kenkyusho was adhered thereto. Anairtight adhesive test for 48 hours was tested. A skin reaction wasestimated according to the following standard with the lapse of 1 hourafter peeling.

[0037] Negative: no reaction is observed at all . . . (−)

[0038] False positive: small dim erythema . . . (±)

[0039] Positive: clear erythema . . . (+)

[0040] Strong positive: erythema, edema and bleb . . . (++)

Examples 1 to 5 and Comparative Example 1

[0041] Using a block copolymer of polystyrene and hydrogenatedpolyisoprene as a styrenic elastomer and polypropylene as a polyolefine,a nonwoven fabric having a polypropylene content shown in Table 1 wasformed by a melt blowing method. An acrylic adhesive having dispersedtherein a highly water-absorbable polymer as a blowing agent was coatedthereon by a reverse-roll coating method. After dried, it was madeporous to form an adhesive film for adhesive bandage. Water-repellentfinish was conducted by diluting a water-repellent composed mainly of afluorine-type resin with water or water:isopropyl alcohol (1:1) in aconcentration shown in Table 1, and then coating the dilutedwater-repellent on the film. The thus obtained adhesive films aredesignated Example Nos. 1 to 5.

[0042] An adhesive film for a commercial adhesive bandage using apolyvinyl chloride film as a support and natural rubber as an adhesiveis shown as a Comparative Example in Table 1. The results of measuringproperties of the adhesive films for adhesive bandage are shown inTable 1. TABLE 1 Com. Example No. 1 2 3 4 5 Ex. 1 Support StyrenicStyrenic Styrenic Styrenic Styrenic Vinyl elast- elast- elast- elast-elast- chloride omer omer omer omer omer film Propylene 30% 30% 30% 40%40% — content Adhesive Acrylic Acrylic Acrylic Acrylic Acrylic Rawrubber Water-repellent finish Solvent Water Water: Water: Water Water —IPA IPA IPA (1:1) (1:1) (1:1) — Concentration 6% 2% 2% + 6% 2% — 2% Testitem (unit) Modulus 0.19 0.15 0.18 0.27 0.24 0.15  5% (kg/inch) Modulus0.27 0.24 0.25 0.43 0.40 0.26  10% (kg/inch) Modulus 0.64 0.61 0.60 0.920.95 1.82 100% (kg/inch) Tensile 1.15 1.15 1.05 1.30 1.33 3.80 strengthat break (kg/inch) Tensile 491 548 457 421 391 340 elongation at break(%) Adhesion to 0.48 0.49 0.42 0.47 0.42 0.37 glass (kg/inch) Moisture3944 4066 3502 3951 3905 35 permeability (g/cm² · 24 hrs)Water >3 >3 >3 >3 >3 >3 repellency to water (hrs)Water- >3 >3 >3 >3 >3 >3 repellency to detergent water (hrs)

[0043] The results of evaluating skin irritation by a patch test for theadhesive bandages using the adhesive films in Example 1 and the adhesivefilm in Comparative Example 1 are shown in Table 2. TABLE 2 Run No.Evaluation 1 C-1 Negative (−) 43 32 False Positive (±)  1 11 Positive(+)  0  1 Strong Positive (++)  0  0

[0044] From the results in Tables 1 and 2, it follows that since theadhesive film for adhesive bandage of the present invention is rich inflexibility and excellent in fitness to a skin, it has less skinirritation, does not stop skin respiration owing to the excellent airpermeability and can prevent a trouble caused by being sticky withperspiration and so forth.

Examples 6 and 7

[0045] Effects provided by the water-repellent finish were observed onthe adhesive film for adhesive bandage having the same composition as inExample 1. A water-repellent composed mainly of a fluorine resin wasused. The results are shown in Table 3. TABLE 3 Example No. 6 7Conditions for water-repellent finish Solvent — Water Amount — 10 wt. %Test item (unit) Moisture permeability 1197 2140 (g/m³ · 24 hrs)Water-repellency to water Water-repellency to detergent >3 hrs >3 hrsAqueous solution 10-20 sec. >3 hrs

[0046] Table 3 reveals that moisture permeability little changes by thewater-repellent finish. Moreover, regarding water repellency to water,since the styrenic elastomer is hydrophobic, a difference due to thewater-repellent finish is not observed. While, regarding waterrepellency to detergent aqueous solution, a difference due to thewater-repellent finish is clearly observed.

[0047] [Effects of the Invention]

[0048] The adhesive bandage using the adhesive film for adhesive bandageof the present invention is, owing to structural characteristics of thestyrenic elastomer, rich in flexibility and excellent in fitness to askin, and can prevent physical skin irritation. Moreover, because ofhigh moisture permeability, skin respiration is not disturbed and skinirritation caused by being sticky with perspiration is also preventable.Blending of the polyolefine increases strength of the nonwoven fabricitself and imparts strength that does not give any trouble in practicaluse. Besides, in case of subjecting the surface to a water-repellentfinish, it is possible to thoroughly prevent permeation of water intothe nonwoven fabric and permeation of water into a pad portion.

We claim:
 1. An adhesive film for adhesive bandage formed by coating anadhesive to a nonwoven fabric comprising 50 to 80% by weight of astyrenic elastomer and 50 to 20% by weight of a polyolefine.
 2. Theadhesive film for adhesive bandage of claim 1 wherein the polyolefine ispolypropylene.
 3. The adhesive film for adhesive bandage of claim 1wherein the stryrenic elastomer is a block copolymer composed of apolystyrene block and a polyisoprene block.
 4. The adhesive film foradhesive bandage of claim 3 wherein the polyisoprene block containshydrogenated polyisoprene.
 5. The adhesive film for adhesive bandage ofclaim 1 wherein the styrenic elastomer is an A-B-A type triblockcopolymer.
 6. The adhesive film for adhesive bandage of claim 4 whereinthe hydrogenation percentage of the polyisoprene block is 80% or more.7. The adhesive film for adhesive bandage of claim 1 wherein theadhesive is a rubbery polymer, an acrylic polymer or a SIS type blockcopolymer.
 8. The adhesive film for adhesive bandage of claim 1 whereinthe adhesive is porous.
 9. The adhesive film for adhesive bandage ofclaim 1 wherein the adhesive is pattern-coated.
 10. The adhesive filmfor adhesive bandage of claim 1 wherein the opposite surface to theadhesive coated surface is subjected to a water-repellent finish.
 11. Anadhesive bandage using the adhesive film of claim 1 .